1. Field of the Invention
The present invention relates a machineroom-less elevator having no machineroom disposed above an elevator shaft.
2. Description of the Related Art
Various machineroom-less elevators having no machineroom disposed above an elevator shaft have been developed and proposed for efficiently utilizing spaces in buildings and for observing regulations regarding the right to sunlight.
For example, in a conventional machineroom-less elevator shown in FIGS. 5 to 7, a cage 1 that is moved vertically in an elevator shaft 2 is guided by a pair of right and left cage-side guide rails 1L and 1R. A counterweight 3 disposed behind the cage 1 is guided by a pair of right and left counterweight-side guide rails 3L and 3R, the counterweight 3 to be vertically moved in the elevator shaft 2 along a rear wall thereof.
A driving apparatus 4 secured on a top of the elevator shaft 2 on a rear wall 2r thereof drives a traction sheave 5 in rotation about a rotational axis horizontally extending in the back and forth direction.
A first diverting sheave 6 capable of being rotated about a rotational axis extending in the back and forth direction is disposed at a position directly below a left end of the driving apparatus 4 on a side of the rear wall 2r of the elevator shaft 2.
A second diverting sheave 7 capable of being rotated about a rotational axis extending in a right and left direction is disposed on a position above the first diverting sheave 6 on a side of a left wall 2L of the elevator shaft 2.
A hoist rope 8 passed round the traction sheave 5 has one end 8a extending downward to be passed round the first diverting sheave 6, then extending upward (8b) to be passed round the second diverting sheave 7, extending downward (8c) from the second diverting sheave 7, horizontally extending (8d) between a pair of right and left cage-side sheaves 1a and 1b which are attached under the cage 1, and then extending upward from the right cage-side sheave 1b to be secured on a front hitch part 9f, so as to suspend the cage 1 in a two-to-one roping arrangement.
The other end 8f of the hoist rope 8 extends downward toward the counterweight 3 to be passed round a counterweight-side sheave 3a and then extends upward to be secured on a rear hitch part 9r, so as to suspend the counterweight 3 in a two-to-one roping arrangement.
In the conventional machineroom-less elevator shown in FIGS. 5 to 7, the driving apparatus 4 is disposed on the rear wall 2r of the elevator shaft 2, and the counterweight 3 is vertically moved along the rear wall 2r of the elevator shaft 2.
In such a constitution, since the first diverting sheave 6 must be disposed below the driving apparatus 4, a sufficiently large vertical stroke of the counterweight 3 cannot be secured because of an interference between the first diverting sheave 6 and the counterweight 3.
In order to secure a sufficiently large vertical stroke of the counterweight 3, when the first diverting sheave 6 is disposed on a higher position, the first diverting sheave 6 comes near the traction sheave 5 and the second diverting sheave 7.
Then, the hoist rope 8 is curved in an S-shape, because extending directions of the part between the traction sheave 5 and the part between the first diverting sheave 6 and the second diverting sheave 7 are suddenly changed.
Thus, there is a fear the durability of the hoist rope 8 may deteriorate.
Further, when the cage 1 stops, a tensile difference is generated in the respective parts 8a and 8b of the hoist rope 8 which are respectively extending upward from the first diverting sheave 6, so that vertical vibrations of the cage 1 may be generated when the cage 1 restarts a vertical movement.
Each torsion angle of the parts 8a and 8b of the hoist rope 8 is 90 degrees, the parts 8a and 8b respectively extending between the traction sheave 5 and the first diverting sheave 6, and between the first diverting sheave 6 and the second diverting sheave 7. Thus, when the hoist rope 8 is formed by a plurality of ropes of a smaller diameter, a displacement of an angle between a direction of rope grooves of the respective sheaves and a direction to which the respective ropes extend from the respective rope grooves is enlarged, so that a generation of noises and vibrations accompanied with a contact of the respective ropes formed by twisting lines with the respective rope grooves can be prevented.
On the other hand, when the driving apparatus 4 and the traction sheave 5 are disposed on the left wall 2L of the elevator shaft 2 in order to solve the above disadvantages, the diverting sheaves must be disposed on the left wall 2L of the elevator shaft 2 for guiding a part of the hoist rope 8 on a side of the rear wall 2r extending downward from the traction sheave 5 to the counterweight 3 on the side of the rear wall 2r. 
In such a constitution, since the driving apparatus 4, the traction sheave 5, and the diverting sheaves are arranged in the back and forth direction when viewed vertically from above, a part of the hoist rope 8 extending downward from the traction sheave 5 to the cage-side sheave 1a is positioned in front of the elevator shaft 2.
Thus, it becomes difficult to conform the part 8d of the hoist rope 8, which horizontally extends between the pair of right and left cage-side sheaves 1a and 1b, to a center of gravity G of the cage 1, when viewed vertically from above.
Further, since the cage-side sheaves 1a and 1b supporting the cage 1 are disposed under the cage, an operation space where an operator inspects the cage-side sheaves 1a and 1b must be secured in a pit disposed on a bottom of the elevator shaft, with a large depth of the pit being needed.
In addition, in order that the hoist rope 8 extends along right and left sidewalls 1c and 1d of the cage 1, the pair of right and left cage-side sheaves 1a and 1b are obliged to project from the right and left sidewalls 1a and 1b of the cage 1. Thus, when a dimension W of the cage 1 in the right and left direction (a direction in which a door is opened and closed) is secured, a dimension L of a cross-section of the elevator shaft in the right and left direction is adversely enlarged.
In other words, when the dimension L of the cross-section of the elevator shaft in the right and left direction is fixed at a certain dimension, the dimension W of the cage 1 in the right and left direction must be reduced.
Maintenance of the driving apparatus 4, the traction sheave 5, and a controller CP fixed to a top sidewall of the elevator shaft must be carried out by elevating the cage 1, on which an operator stands, to an uppermost position.
On the other hand, maintenance of the cage-side sheaves 1a and 1b must be carried out by lowering the cage 1 to a lowermost position in the pit.
Thus, in the conventional machineroom-less elevator, a maintenance operation cannot be efficiently carried out because an operator must move up and down between an uppermost floor and a lowermost floor of a building.
Another machineroom-less elevator has been proposed in which the diverting sheave 7 in FIG. 5 is replaced with a traction sheave, and a driving apparatus is disposed such that a rotational axis thereof extends in the same direction as that of the part 8d of the hoist rope 8 extending between the cage-side sheaves 1a and 1b. With a rotation of the traction sheave, the counterweight 3 is vertically moved behind the cage 1.
However, the machineroom-less elevator of such a constitution has some disadvantages to be solved, with respect to a durability of the hoist rope, supporting manner of the driving apparatus, vibrations, and so on.
Therefore, it is a first object of the present invention to provide a machineroom-less elevator where a counterweight is vertically moved behind a cage, which is capable of solving the above disadvantages of the conventional art. In the machineroom-less elevator, a vertical stroke of a counterweight can be sufficiently secured, while a durability of a hoist rope is improved by mitigating a drawing of the hoist rope. Since no tensile difference is generated in respective parts of the hoist rope, vertical vibrations of the cage are prevented when the cage restarts a vertical movement. Further, a generation of noises and vibrations accompanied with a contact of rope grooves of respective sheaves with the hoist rope can be prevented.
It is a second object of the present invention to provide a machineroom-less elevator which is improved such that a depth of a pit in a bottom of an elevator shaft is reduced, and that a maintenance operation can be centrally carried out above a cage. Further, a dimension of a cross-section of the elevator shaft in the right and left direction is restrained to be small relative to a width dimension of the cage. A hoist rope can be drawn such that a part of the hoist rope is conformed to a center of gravity of the cage when viewed vertically from above.